#include <stdio.h>
#include <stdlib.h>
#include <math.h>
int main()
{
    double d,p,r,m;
    scanf("%lf%lf%lf",&d,&p,&r);
    m=log(p/(p-d*r))/(log(1+r));
    if(m>=0.0)
    printf("%.1lf\n",m);
    else if(p==0||d==0)printf("0.0");
    else printf("God");
    return 0;
}
